feat(transform): individualise article costs with per-country Eurostat data

Add real per-country cost data to ~30 calculator fields so pSEO articles
show country-specific CAPEX/OPEX instead of hardcoded DE defaults.

Extractor:
- eurostat.py: add 8 new datasets (nrg_pc_205, nrg_pc_203, lc_lci_lev,
  5×prc_ppp_ind variants); add optional `dataset_code` field so multiple
  dict entries can share one Eurostat API endpoint

Staging (4 new models):
- stg_electricity_prices — EUR/kWh by country, semi-annual
- stg_gas_prices         — EUR/GJ by country, semi-annual
- stg_labour_costs       — EUR/hour by country, annual (future staffed scenario)
- stg_price_levels       — PLI indices (EU27=100) for 5 categories, annual

Foundation:
- dim_countries (new) — conformed country dimension; eliminates ~50-line CASE
  blocks duplicated in dim_cities/dim_locations; computes ~29 calculator cost
  override columns from PLI ratios and energy price ratios vs DE baseline;
  NULL for DE so calculator falls through to DEFAULTS unchanged
- dim_cities — replace country_name/slug CASE blocks + country_income CTE
  with JOIN dim_countries
- dim_locations — same refactor as dim_cities

Serving:
- pseo_city_costs_de — JOIN dim_countries; add 29 camelCase override columns
  auto-applied by calculator (electricity, heating, rentSqm, hallCostSqm, …)
- planner_defaults — JOIN dim_countries; same 29 cost columns flow through
  to /api/market-data endpoint

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

transform/sqlmesh_padelnomics/models/serving/planner_defaults.sql

@@ -7,6 +7,10 @@
 --   2. Country-level: median across cities in same country
 --   3. Hardcoded fallback: market research estimates (only when no Playtomic data)
 --
+-- Cost override columns from dim_countries (Eurostat PLI + energy price indices) are
+-- included so the planner API pre-fills country-adjusted CAPEX/OPEX for all cities.
+-- NULL = fall through to calculator.py DEFAULTS. DE always NULL (baseline preserved).
+--
 -- Units are explicit in column names. Monetary values in local currency.
 
 MODEL (
@@ -125,6 +129,37 @@ SELECT
     ELSE 0.2
   END                                           AS data_confidence,
   COALESCE(cb.price_currency, ctb.price_currency, hf.currency, 'EUR') AS price_currency,
+  -- Cost override columns (Eurostat PLI + energy prices via dim_countries).
+  -- NULL = fall through to calculator.py DEFAULTS. DE always NULL (baseline).
+  dc.electricity,
+  dc.heating,
+  dc.rent_sqm,
+  dc.insurance,
+  dc.cleaning,
+  dc.maintenance,
+  dc.marketing,
+  dc.water,
+  dc.property_tax,
+  dc.outdoor_rent,
+  dc.hall_cost_sqm,
+  dc.foundation_sqm,
+  dc.land_price_sqm,
+  dc.hvac,
+  dc.electrical,
+  dc.sanitary,
+  dc.parking,
+  dc.fitout,
+  dc.planning,
+  dc.fire_protection,
+  dc.floor_prep,
+  dc.hvac_upgrade,
+  dc.lighting_upgrade,
+  dc.outdoor_foundation,
+  dc.outdoor_site_work,
+  dc.outdoor_lighting,
+  dc.outdoor_fencing,
+  dc.working_capital,
+  dc.permits_compliance,
   CURRENT_DATE                                  AS refreshed_date
 FROM city_profiles cp
 LEFT JOIN city_benchmarks cb
@@ -134,3 +169,5 @@ LEFT JOIN country_benchmarks ctb
   ON cp.country_code = ctb.country_code
 LEFT JOIN hardcoded_fallbacks hf
   ON cp.country_code = hf.country_code
+LEFT JOIN foundation.dim_countries dc
+  ON cp.country_code = dc.country_code